1. Field of the Invention
This invention relates to a mold article ejecting device used for an injection molding apparatus, more particularly to a mold article ejecting device with an injector rod which can be moved in a to-and-fro movement and which is detachably coupled to an ejector plate for removing a molded article from a mold cavity of an injection molding apparatus.
2. Description of the Related Art
Referring to FIGS. 1 and 2, a conventional injection molding machine 100 is shown to include a movable plate 12 which is mounted on an upper support plate 16, a stationary plate 11 and a molded article ejecting device 13 which are mounted on a lower support plate 17. The movable and stationary plates 12,11 have cup-shaped mold portions 121,110, and abut against each other to form a cup-shaped mold cavity 14 in an injection position, as shown in FIG. 1. A hopper 161 and a sprue channel 163 are formed through the upper support plate 16 to communicate with the mold portion 121 such that liquid molding material flows from the hopper 161 through the sprue channel 163 into the mold cavity 14.
Partition plates 18 are mounted between the stationary plate 11 and the lower support plate 17 so as to confine a space 111 for accommodating the ejecting device 13. The ejection device 13 includes a distal ejector plate 131, a proximate ejector plate 135, ejector pins 132, and springs 133. The ejector pins 132 have inner segments which are secured between the proximate and distal ejector plates 135,131, and outer segments which extend slidably through the mold portion 110 of the stationary plate 11. The springs 133 are mounted between the proximate ejector plate 135 and the stationary plate 11. An ejector rod 20 is inserted into a through bore 113 in the lower support plate 17, and is actuated to press the distal ejector plate 131 so as to move the distal ejector plate 135 and the ejector pins 132 against the biasing action of the springs 133, thereby knocking out a molded article 19 from the stationary plate 11. The distal ejector plate 131 is retracted by virtue of the biasing force of the springs 133 when the ejector rod 20 is moved back so as to retract the ejector pins 132.
Since the ejector pins 132 are retracted by means of the springs 133, the space 111 has to be large enough to receive the springs 133, thereby resulting in bulkiness of the machine 100. Moreover, long term use will result in fatigue of the springs 133, so that the ejector pins 132 cannot be retracted completely.
Referring to FIGS. 3 and 4, another conventional injection molding machine 200 is shown to include a stationary plate 21, a movable plate 22, a transverse plate 24 which is movable transversely on the stationary plate 21 and which is actuated by a control rod 25 that is mounted on the movable plate 22. Since the transverse plate 24 is designed to be moved to a position where an ejector pin 27 projects outwardly of the stationary plate 21 before the movable plate 22 abuts against the stationary plate 21, fatigue of springs 28 is likely to result in collision between the transverse plate 24 and the ejector pin 27.